BANDO AAE TEORIA
Fondi
300 kEu / anno
Circa 10 programmi finanziati ogni anno
selezionati da referee stranieri (16 richiesti)
Risultati scientifici dopo il secondo anno
Laura Maraschi
Modeling the properties of baryon gas in
the large scale structure of the universe
•  Univ. Bologna:
Lauro Moscardini
•  Univ. Roma Tre:
Enzo Branchini
•  Oss. Astr. Torino:
Giuseppe Murante
•  Oss. Astr. Trieste:
Matteo Viel
Tool: High-resolution
hydrodynamical simulations
with a detailed description of the
physical processes acting on
ICM and WHIM.
Main goal: Characterization of
the baryon gas in galaxy
clusters and in the cosmic web
for a realistic comparison with
present and future X-ray
observations.
SCIENTIFIC JUSTIFICATION
To characterize the thermodynamic of
the X-ray emitting plasma at the virial radius
  Which ngas, T and Sb values do we expect at Rvir ?
  Are simulated X-ray clusters consistent with the observed
ones in the outskirts ?
Implications
  To calibrate the masses (gas and dark matter) in local
galaxy clusters to use them as cosmological probes
  To study the accretion of primordial gas in cluster DM halos
ICM at Rvir: Simulated clusters
4 massive objects (Mvir : 1.9-3.4e15, Tvir : 5.5-9.9 keV) simulated
using 4 different physical models: gravitational heating plus
artificial viscosity, cooling, star formation, feedback, thermal conduction
ngas
Roncarelli, Ettori et al 06
Tgas
ICM at Rvir: Simulated clusters
ngas
Tgas
Unresolved CXB w. CXO
(Hickox & Markevitch 05)
Sb [0.5-2 keV]
 Independently from the physics, just gravity
 We know what we’d observe at R200 (Tgas, Sb): X-ray
observations & simulations provide a consistent picture with
ngas~r-2.6 & Tgas~r-0.4 & Sb~1e-16erg/s/cm2/arcmin2
Intergalactic filaments at z~3 & clusters and groups at z~0 Borgani & Viel 2009, MNRAS, 392, L26
Intergalactic medium @ z=3
Standard model (left)
Model with pre-heating (right)
Intracluster medium @ z=0
Standard model (left)
Model with pre-heating (right)
The goal: to have a pre-heating model
able to reproduce at the same time the
entropy profiles of clusters and
groups and the properties of
intergalactic medium
The entropy level in galaxy groups at z~0
Borgani & Viel 2009, MNRAS, 392, L26
Sun et al. ‘08: Chandra
archival data of 40
nearby groups.
No pre-heating:
Correct entropy level at
r500
R500
Too low entropy at r2500
 Need Kfl>100 keV cm2
consistency with data to
reach.
R2500
Combined with Ly-a data:
Either prevent heating
low-δ regions at high z
Or heat at relatively low z
Acceleration of high energy particles
in galaxy clusters
PI: Gianfranco Brunetti (INAF-IRA, Bologna)
Pasquale Blasi (INAF- Oss Arcetri, Firenze)
Giancarlo Setti (Univ. Bologna)
Claudio Gheller (CINECA, Bologna)
Rossella Cassano (INAF-IRA, Bologna)
Franco Vazza (INAF-IRA, Bologna)
Roberto Fusco-Femiano (INAF- IASF, Roma)
Matteo Murgia (INAF- Oss Cagliari)
Daniele Dallacasa (Univ. Bologna)
Aims: Particle acceleration mechanisms in galaxy clusters,
shocks & turbulence in galaxy clusters,
non thermal emission from galaxy clusters (gamma, X, radio)
Methods: teoretical models & numerical simulations
OzLens - Sydney, 30 Sep 2008
Simulations : Shocks in Galaxy Clusters
Vazza, Brunetti, Gheller 2008
OzLens - Sydney, 30 Sep 2008
Shocks in Galaxy Clusters
Vazza, Brunetti, Gheller 2008
OzLens - Sydney, 30 Sep 2008
Radio Power
Turbulent acceleration in GC (Brunetti +al. 2008, Nature 455,944)‫‏‬
loss
Acc
Frequency
Low frequency
High frequency
OzLens - Sydney, 30 Sep 2008
Alfvenic acceleration in GC
Brunetti, Blasi, Cassano, Gabici 2008,09
Syn
EGRET
πo
IC
Fermi
OzLens - Sydney, 30 Sep 2008
Veritas
High Energy Emission from Accreting
Massive Black Holes along the Cosmic
History
Coordinatore: Francesco Haardt!
RU1: Universita’ dell’Insubria@Como (P.I.: F. Haardt)!
RU2: Universita’ di Milano/Bicocca (P.I.: M. Colpi) !
Star bulge!
Gas disk!
100 pc!
Density wake behind !
at pericenter!
Net effects: orbital decay and circularization!
Density wake in front !
at apocenter!
...and linking accretion to dynamics.!
Orbital separation !
At pericenter passages,
the
secondary
hole
collects gas that can be
accreted.!
As the orbit shrinks and
circularizes accretion is
more stable, and variability
reduced.!
L/LEddxt! M1! M2!
Self-Consistent Modelling of the Photo-Ionized
Environment of Astrophysical Sources
PI: Fabrizio Nicastro (INAF-OAR)
Co-Is: D. Guetta (INAF-OAR), G. Matt, S. Bianchi (RomaTre)
Collab.: Y. krongold (UNAM, Mexico), N. Brickhouse (CfA, USA), M. Elvis (CfA, USA), S. Mathur (OSU, USA)
Personale: M. van Adelsberg (INAF-OAR)
•  Elaborazione codice per la produzione di spettri (In
banda UV e X) da plasma ionizzato in equilibrio, in
regime otticamente sottile e per ioni nelo stato
fondamentale
•  Estensione del codice ai casi (a) otticamente spesso
(trasferimento radiativo), e (b) ioni su livelli accitati
(calcolo della popolazione dei livelli)
•  Estensione del codice ai casi (a) di non equilibrio e
(b) dipendente dal tempo
PHASE (PHotoionized Absorber Spectral Engine)
• 
• 
• 
• 
• 
Most up-to-date atomic data-base (for H to Zn)
Covers O-X-rays: more than 3000 resonant transitions
Solves for Ionization and Level Population Balance (C & P)
Computes proper line profile (Voigt) + Radiative Transfer
Interfaces with public fitting packages (e.g. Sherpa, XSPEC)
Warm Absorbers = AGN Outflows
Cosmologically important: Feedback
NGC 3783
Chandra MEG
900 ksec
exposure
PHASE+TEPHOT
FeII Level Population Evolution in Time:
General GRB light-curve
(Time-Evolving PHOToionization)
OVI-VIII Ionization Balance Evolution in
Time:
Typical AGN X-ray Ligh-curve (NGC 4051)
D ~ pc
Ground
n=2
n=3
D ~ kpc
Excellent Distance diagnostics!
Excellent Density diagnostics!
Simulazioni MHD di plasmi relativistici
e della loro emissione ad alte energie
Responsabile: R.Bandiera
Istituto: Oss. Astrof. Arcetri
Partecipanti: E.Amato, L.Del Zanna, F.Pacini, D.Volpi
Crab
PULSAR WIND NEBULAE
Raggi X
I venti relativistici e magnetizzati
prodotti da pulsar sono rallentati
in uno shock terminale, dove ha
luogo accelerazione di particelle.
Dopo lo shock si forma una
nebulosa non termica, che mostra
nei raggi X una tipica morfologia
getto – toro.
Simulazioni MHD basate su
modelli di vento magnetizzato con
un flusso di energia maggiore
all’equatore che al polo (e.g. Del
Zanna et al. 2004, 2006) riproducono
bene quanto osservato.
Vela
Raggi X
Alcuni Recenti Risultati
Modelli dello spettro integrato dell’emissione di una Pulsar
Wind Nebula, su un’ampia gamma spettrale, dal radio ai
raggi gamma.
In figura il caso della Crab Nebula.
Variazioni multiple
di indice spettrale,
anche se con una
distribuzione delle
particelle iniettate a
legge di potenza, è
un risultato che si
ottiene soltanto
usando trattazioni
multi-dimensionali.
Mappe simulate dell’emissione in
raggi gamma (Compton inverso).
Le dimensioni sono superiori a
quelle in banda X ma decrescono
con l’energia (eccetto che nella
regione equatoriale).
(Volpi et al. 2008)
La diminuzione delle dimensioni
con l’energia è in accordo con le
mappe in raggi gamma (risolte
solo marginalmente), ottenute
con MAGIC.
NON-LINEAR PARTICLE
ACCELERATION AT SHOCK
WAVES: IMPLICATIONS FOR X/
GAMMA RAY ASTRONOMY AND
THE ORIGIN OF COSMIC RAYS
PI: Pasquale Blasi
Staff
Members:
E.
Amato,
R.
Bandiera,
P.
Lipari,
M.
Vietri
Postdoc
and
students:
D.
Caprioli,
G.
Cassam‐Chennai,
G.
Morlino
Main Goals
1. Complete the development of a non-linear theory of diffusive particle acceleration at non-relativistic shocks
2. Application of the theory to the case of individual Supernova remnants which show non-thermal Activity
3. Application of the theory to the origin of galactic Cosmic rays
4. Investigation of the implications of the theory for the
Transition from Galactic to extragalactic Cosmic Rays
MAIN RESULTS!
WE DID COMPLETE THE THEORY WITH !
AMPLIFICATION OF MAGNETIC FIELD!
BY THE ACCELERATED PARTICLES…!
…AND WITH THE DYNAMICAL REACTION OF THE MAGNETIC
FIELD ON THE PLASMA !
WE APPLIED THE NLDSA TO THE CASE OF RXJ1713 WHICH HAS
RECENTLY BEEN DETECTED AT TeV BY HESS!
WE ESTABLISHED THAT MAGNETIC FIELD AMPLIFICATION !
LEADS TO ACCELERATION OF PROTONS TO ~106 GeV (knee)!
WE DETERMINED THE CONNECTION BETWEEN SNR AND CR!
THROUGH THE COMPLEX PHENOMENON OF ESCAPE!
The case of RXJ1713
Aharonian et al. 2007
The case of RXJ1713
MORLINO,
AMATO
&
BLASI
2009
FERMI
HESS,
CTA
H
L
Spectral and Timing Properties of
Isolated Neutron Stars, Magnetars and
Related Objects
PI: R. TUROLLA
PADOVA UNIT: R, TUROLLA, L. NOBILI, A. ALBANO, L. PAVAN,
L. ZAMPIERI
OAR UNIT: L. STELLA, GL. ISRAEL, E. BOZZO, M. BURGAY,
S. DALL’OSSO
Magnetar Spectra
R. Turolla, A. Albano, F. Bernardini, G.L. Israel, L. Nobili, L. Pavan,
N. Rea, S. Zane
Observational evidence that the Soft Gamma
Repeaters and the Anomalous X-ray
Pulsars host an ultra-magnetized neutron star,
a magnetar (B > BQED ~ 4.4x1013 G)
Quiescent X-ray emission (0.5-10 keV) from
SGRs/AXPs modeled by a thermal component
(kT ~ 0.5 keV) plus a power law tail (Γ ~ 1.5-4).
A high-energy (~ 15-200 keV) tail detected by
INTEGRAL in many sources
BB
PL
HE PL
Magnetar magnetospheres are twisted, i.e.the B-field has a
non-vanishing toroidal component. Large currents (j ≫ jGJ)
are required to support the field
A physical emission model: thermal photons emitted by the
cooling star surface undergo resonant (cyclotron)
up-scattering onto magnetospheric charges
A twisted dipolar magnetoshpere
A Monte Carlo code has been developed to solve radiative transfer in the
magnetosphere. Proper account for photon propagation in a strongly
magnetized medium and magnetic Compton scattering
Seed blackbody
Conservative (magnetic Thomson) scattering
Spectral model implemented in XSPEC
Magnetic Compton scattering
HE cut-off due
to electron recoil
Resonan Cyclotron
Scattering explains
magnetar spectra in
the soft X-ray range.
Extension to the
10-200 keV band
under way
Supergiant Fast X-ray Transients:
Standard HMXBs with standard NSs?
~8 ks
ISGRI Science Window image sequence
XTEJ1739-302
Like many
other HMXB:
SAX J1818.6-1703
OB supergiant companion stars
  Outburst X-ray luminosities
~1036-1037 erg s-1
 
(Sguera et al. 2005)
At difference with many others
HMXBs:
Extremely high X-ray luminosity variations
between outburst and quiescence
LX~104-105
  Sporadic outbursts lasting only few hours
 
LX>2x103
t~500s
(for periodic SFXT see Sidoli et al. 2007)
 
Evidences of Pspin~1000-2000 s (>300 s)
(Sguera et al. 2006; Walter et al. 2006)
(Sakano et al. 2002)
OzLens - Sydney, 30 Sep 2008
SFXT: the most extreme case ever observed...
~1037 erg/s
IGRJ17544-2619
Caught by Chandra
from quiescence to
outburst
5
LX~10
t~5
h
~1036 erg/s
~1033 erg/s
~1032 erg/s
OzLens - Sydney, 30 Sep 2008
(In't Zand 2005)
The Gated accretion model for SFXT sources:
OB
STA
R
NS R
An interaction
very similar to
the Earth - Solar
Wind case:
matter flows
away along the
magnetosphere
(and does not
accrete..)
a
WIN
D
BOW SHOCK
QUIESCENCE: Accretion is inhibited during most of the orbital motion of the NS around it
supergiant companion by a MAGNETIC BARRIER ( gives LX~1032-1034 erg/s )
  OUTBURST: Sporadic outbursts due to episodes of enhanced accretion due to the presence
of “clumps” from the wind of the supergiant companion ( gives LX~1036-1037 erg/s )
 
Requires Neutron Star magnetic field >1014 G instead of the typical 1012 G
Supergiant Fast X-ray Transients might host
MAGNETARS!!!
OzLens - Sydney, 30 Sep 2008
Quest’anno abbiamo finanziato un nuovo
progetto (PI S. Orlando, OA Pa)
Sviluppo di simulazioni MHD per
fenomeni di accrescimento e dischi
in oggetti stellari giovani